Decades of overfishing in the Gulf of Mexico have stripped the five-state region of tens of millions of dollars in economic activity in recent years, according to a report released Tuesday.

The study by Ecotrust, a Portland, Ore.-based conservation group, found that Gulf states, including Texas, lost $13 million annually between 2005 and 2009 because of fewer recreational fishing trips targeting severely depleted red snapper.

The amount represents money that was not spent on boat rentals, charter fees, tackle and bait and other direct expenses.

The group estimated the losses increased to $33 million a year when spending on restaurants, hotels and other related businesses is included.

The Gulf region also lost millions each year because of overfishing of gag, gray triggerfish and greater amberjack, the study found.

The Pew Environment Group, which paid for the study, said the findings make the economic case for extending federal law that requires science-based annual catch limits to rebuild fisheries stocks.

The Magnuson-Stevens Fishery Conservation and Management Act is up for reauthorization this year.

The group said the analysis underscores the benefit of allowing stocks to grow to a sustainable level by showing how much additional money anglers would spend.

Some fishermen are seeking a change in the law after the National Marine Fisheries Service set the shortest snapper season in Gulf history, just 40 days, despite the healthiest population of red snapper since the 1970s. A decade ago, the season lasted as long as 194 days.

"They have removed fishermen from the water, and they do not want us to go back," said Capt. Tom Hilton, who owns and operates Hilton's Fishing Charts in Arcola.

The Fisheries Service has said the catch limits under the Magnuson-Stevens law have been successful elsewhere, with a record six stocks of fish returning to healthy levels in the last year. They include the Bering Sea snow crab, the haddock in the Gulf of Maine and the Chinook salmon along the Northern California coast.

In all, 27 fish stocks have recovered since 2000.

The red snapper stock is on pace for recovery by the early 2030s. Fish stocks must be 40 percent of their historical level to be considered rebuilt.

Red snapper must grow larger and older to reach its most productive spawning years. One 24-inch fish can produce as many eggs as 212 17-inch fish can, said Holly Binns, who leads Pew's conservation efforts in the Gulf.

"Full recovery will take another couple decades," Binns said, "but we will see some significant gains in the next five to 10 years, and that will mean higher catch limits."